I said I wasn't ready and then changed my mind

So I am in my first relationship (I'm 16) and my boyfriend and I were at the park. There was no one else there of course and we were on this bench talking and kissing a little. I told him I wasn't ready to do anything more than that and then literally 10 minutes later I said I changed my mind. So he fingered me and everything was fine. But now I feel weird about it. I just feel dirty I guess. I can't explain it. Has this happened to anyone else? I don't know how to feel. I'd like to make it clear I DON'T BLAME HIM FOR ANYTHING. I FULLY CONSENTED. I don't want this to be taken as I'm blaming him for my feelings or anything.